1. Field of the Invention
The present invention relates to a radio transmitting/receiving system. More particularly, the present invention relates to a wireless packetization apparatus for transmitting and/or receiving multimedia data including video data in a radio transmitting/receiving system, and a method thereof.
2. Description of the Related Art
In general, a radio transmitter and a radio receiver employing a phase 1 standard in CDMA 2000 are formed of high-level layers as shown in FIG. 1.
Codec-related standards such as H.324M. H.323, and T.120 correspond to an application layer. A physical layer performs channel coding, PN spreading, and modulation. A media access control (MAC) layer includes a signaling unit (not shown) and a radio link protocol (hereinafter referred to as RLP) (not shown), and the RLP converts payload on the application layer transmitted through a radio path into an input format on the physical layer. The physical layer among the three layers is mainly realized by hardware, and its flexibility is small when its hardware is determined by a standard. However, flexibility can be given to the application layer considering its network-independent portion.
Referring to FIG. 2, one RLP corresponds to each of a number N of applications (application 1, application 2, . . . , and application N). The RLP is connected to a physical layer 240 through a MUX sub-layer 230.
The MUX sub-layer 230 multiplexes a number N of received RLPs adaptively to a protocol data unit (PDU). Here, the multiplex protocol data unit (MUX-PDU) is available in a case where a channel bit error rate is less than 10-6.
Referring to FIG. 3, a TYPE field 310 denotes a frame type, that is, re-transmitted frame or a new frame, and a SEQ field 320 denotes a frame number or a sequence number, and a DATA field 330 denotes a payload received from an application layer. An RLP type 3 as shown in FIG. 3 is a mode, which even allows data to be re-transmitted, and the length of the DATA field 330 is variable in unit of byte. In this case, the length of the entire RLP frame is fixed. However, when even a part of header portions 310 and 320 of the RLP frame is damaged, it is impossible for a recipient to know the exact length of the DATA field 330, and consequently, RLP decoding is not possible.